diff --git a/ext/AccessorsTestExt.jl b/ext/AccessorsTestExt.jl
index ac0e06fe..c6edc8d7 100644
--- a/ext/AccessorsTestExt.jl
+++ b/ext/AccessorsTestExt.jl
@@ -18,12 +18,12 @@ function Accessors.test_getset_laws(lens, obj, val1, val2; cmp=(==))
     @test cmp(obj12, obj2)
 end
 
-function Accessors.test_modify_law(f, lens, obj)
+function Accessors.test_modify_law(f, lens, obj; cmp=(==))
     obj_modify = modify(f, obj, lens)
-    old_val = lens(obj)
-    val = f(old_val)
-    obj_setfget = set(obj, lens, val)
-    @test obj_modify == obj_setfget
+    old_vals = getall(obj, lens)
+    vals = map(f, old_vals)
+    setall(obj, lens, vals)
+    @test cmp(obj_modify, obj_setfget)
 end
 
 function Accessors.test_insertdelete_laws(lens, obj, val; cmp=(==))
diff --git a/test/test_getsetall.jl b/test/test_getsetall.jl
index 5424e668..aeef5931 100644
--- a/test/test_getsetall.jl
+++ b/test/test_getsetall.jl
@@ -1,7 +1,7 @@
 module TestGetSetAll
 using Test
 using Accessors
-using Accessors: test_getsetall_laws
+using Accessors: test_getsetall_laws, test_modify_law
 using StaticNumbers
 using StaticArrays
 
@@ -155,14 +155,15 @@ end
     @test_broken ([1, 2], [3.0, 4.0, 5.0], ("6",)) == @inferred setall(obj, @optic(_ |> Elements() |> Elements()), (1, 2, 3., 4., 5., "6"))
 end
 
-@testset "getall/setall consistency" begin
+@testset "getall-setall laws" begin
     for (optic, obj, vals1, vals2) in [
-            (Elements(), (1, "2"), (2, 3), (4, 5)),
-            (Properties(), (a=1, b="2"), (2, 3), (4, 5)),
+            (Elements(), (1, false), (2, 3), (4, 5)),
+            (Properties(), (a=1, b=false), (2, 3), (4, 5)),
             (If(x -> x isa Number) ∘ Properties(), (a=1, b="2"), (2,), (4,)),
             (@optic(_.b |> Elements() |> Properties() |> _ * 3), (a=1, b=((c=3, d=4), (c=5, d=6))), 1:4, (-9, -12, -15, -18)),
         ]
         test_getsetall_laws(optic, obj, vals1, vals2)
+        test_modify_law(x -> x + 1, optic, obj)
     end
 end